A lot of people are too negative these days. There is a difference between realism/honesty and negativity. You can approach things from different perspective and it doesn't necessarily always have to be the negative one.
1. Go out for a walk everyday
Alone. Walk your dog. Walk on your own. Just for 10-30 minutes. It really clears your mind and helps you feel better.
2. If you can afford to, get a pet
I'm an animal lover. I had very weird pets and very conventional ones. I love animals and they all have different personalities, any animal owner will say that is true! Pets are very loving and can make your bad day a lot better. Even volunteering at an animal shelter can also make you feel a lot better. If animals aren't your thing, try a human shelter.
3. Give yourself a break
Don't be too hard on yourself. Sometimes, that is unproductive and does no good. Do push yourself to work harder, but don't beat yourself up for everything.
4. Find time for the things you love
Whether its hanging out with a loved one, drawing, reading a good book or whatever it is you like doing, organize your time and try to squeeze it into your schedule. I have a very busy schedule, but I still have a lot of time for my hobbies and the things I like doing.
5. Learn to love your own company
You are not always going to be surrounded by others, and that's completely fine! Learn to cope with being alone and enjoying quality time with yourself. Too many people do not know how to do that, but believe me this is the best thing you can do for yourself, is to be independent so when the time comes that not that many people are around you, you learn how to deal with it.
6. Delete your social media
The best thing I have done for myself. Some social media platforms are very toxic, and keeping yourself in those kinds of places will only worsen your mood both consciously and subconsciously.
7. Cut negative people out of your life
Now do not cut everyone off just for disagreeing with you or making you feel bad, sometimes that negative person in your life could be yourself. But if someone is obviously worsening your mental state, continues to treat you badly and never acknowledges their mistakes, cut them out of your life.
Whether it's a family member or a bad friend, never feel guilty for keeping them out of your life if they won't stop making your life worse.
Have a nice day :)